Embryo Culture

n July 25, 1978, Louise Brown- the first baby conceived in laboratory with in-vitro fertilization (IVF) technology was born in Oldham, UK. The doctor Patrick Steptoe, gynaecologist, expert in laparoscopy, and the scientist Robert Edwards, responsible for this historical event received the Nobel Prize in 2010. Since 1978 more than 5 million children have been born from assisted reproduction technique (ART) worldwide. That is how far ART and Embryology Training Courses have taken us!

In a country like India, considering our burgeoning population, it might seem hard to believe that infertility is indeed a huge cause of concern. Owing to changes in lifestyle as well as hormonal and other miscellaneous causes, the percentage of infertile couples has continued to increase over the last few years. However the only glimmer of hope is the worldclass Embryology Training Courses available that makes the lives of infertile couples easier with the ART methods.

Scientists have made great improvements in the last decades. However, there are still many issues that are yet to be resolved. Only 10–30% of all embryos replaced in the uterus implant and result in a live baby. It is for this very reason that embryology training courses now focus more on improving embryo culture and culture media to choose to reduce the embryonic stress.

Culture media, where the embryos develop and grow for 5-6 days, are made specifically in order to replicate the physiological conditions of the female reproductive tract. A large number of different media formulations and culture systems have been employed for the development of the human embryo. These media have highly varied formulations, ranging from simple salt solutions to complex tissue culture media.

There are two different types of medium: the “individual” and “sequential”. The first type is a single step medium which is use from the fertilization until the blastocyst stage (5/6 days after fertilization). Sequential media, instead, are used and changed at specific time: the “Fertilization Medium” from egg collection to fertilization, the “Cleavage Medium” from fertilization until day 3 of developing and the “Blastocyst Medium” from day 3 until day 5/6. The main difference in these mediums is due to the presence of compounds that provide energy to the embryo in the early stage of development, and in particular to pyruvate, lactate and glucose.

Several studies have shown that the percentage of oxygen in uterus, in different species of mammals, varies between 2% and 8%, i.e. it is lower compared to atmospheric oxygen (8). Other studies have also shown that the culture of embryos with an oxygen concentration of 5% is associated with higher pregnancy rates. It is evident that the reduction of oxygen in culture is directly proportional to the reduction of ROS (Reactive Oxygen Species). Embryo exposed to ROS will increase the demand for antioxidant enzymes to keep the homeostatic control and this condition may reduce the potential of this embryo to generate a pregnancy. ROS can induce damage both biological membranes and organelles contained inside the cell, therefore reducing the percentage of oxygen also diminish their effects .

Culture of embryos in suboptimal conditions compels the embryo to undergo adaptations, the consequences of which are lower pregnancy rates. Multiple factors such as temperature, PH and gas phase, both carbon dioxide and oxygen levels, if used at the non-physiological value, can have a detrimental impact on the pregnancies and deliveries rate. In conclusion, the pre-implantation mammalian embryo from different species seems to be sensitive to the environment in which it develops: the culture conditions. This sensitivity may lead to long-term alterations, which have implications for clinical health.

Considering the fact that nowadays around 1-3% of new born in developed countries are born due to in-vitro assisted reproductive technologies (ART), this is an extremely crucial aspect to keep in mind.